I've been testing my gallery plugin using local and remote URLs.
This seemed reasonable until I realised that it breaks the release process.
This is because the release needs to test an updated environment, but the environment is only updated by the release. So my tests would pass on local dev, but fail when run through the CI, which could only see the remote URL.
Note: I just remembered that there's actually a way to expose a local URL to other internet users, I didn't try this.